1. Field of the Invention
The invention relates to an endoscope device affording the autoclave sterilization (high pressure and high temperature vapor sterilization).
2. Related Art Statement
These days, in the medical field, endoscopes inspecting a deep portion in a body are widely used for inspecting a deep portion in a body cavity by inserting an elongated insertion part into the body cavity or the like, and performing medical treatment by means of treatment tools as desired. It is essential to surely disinfect and sterilize these medical endoscopes to prevent the transmission of infectious disease or the like.
Conventionally, gases such as ethylene oxide gas and so on, and antiseptic solutions have been used for disinfecting and sterilizing. However, sterilizing gases or the like contain virulent poison as is well known, and so regulations have restricted their use to prevent environmental pollution. Also, another problem with sterilization is that endoscopes cannot be used immediately after sterilization because it takes time to perform aeration for removal of gases adhering to associated equipment after sterilization. Yet another problem is that these gases cause the running fee to become high.
On the other hand, the problem with antiseptic solutions is that managing antiseptic solutions is complex and troublesome and the disposal treatment of antiseptic solutions is expensive.
Hereupon, autoclave sterilization (high pressure and high temperature vapor sterilization) is recently prevailing as it can be used as sterilization of endoscope equipment immediately after sterilization without any troublesome operation and inexpensively.
A typical condition for autoclave sterilization includes American Standard Code ANSI/AAMI ST37-1992 approved by the Society of American Standard Code and published by the Society of Medical Equipment Research and Development, in which the pre-vacuum type prescribes a sterilization process at 132xc2x0 C. for four minutes, and the gravity type prescribes a sterilization process at 132xc2x0 C. for ten minutes.
However, a high pressure and high temperature vapor in such autoclave sterilization is transmitted through polymeric materials, such as rubber, plastics or the likexe2x80x94which constitute an endoscopexe2x80x94adhesives and so on. In particular, conventionally used adhesives such as epoxy resins are susceptible to deterioration by high temperature vapor, which results in peeling-off of an adhesive, such that it becomes possible for vapor to enter into the interior of a lens system.
Accordingly, where an endoscope of conventional watertight construction, made watertight, is loaded into an autoclave device for sterilization, vapor will enter the interior of the endoscope structure.
Also, to prevent an outer skin tube from bursting at a curved section during the vacuum process prior to the sterilization process, an endoscope may be charged into an autoclave sterilization apparatus with its outside and inside communication when autoclave sterilization is to be performed. However, by applying this method, vapor for autoclave sterilization will positively enter the endoscope.
In the case where autoclave sterilization is applied to an endoscope, in which an objective lens is fixed by means of an adhesive, disclosed in, for example, Japanese Utility Model Application No. 188081/1985, vapor will enter the objective optical system through the adhesive. Accordingly, when taking out such endoscope after the autoclave sterilization and inspecting the same under an eyepiece unit, the lens becomes frosted and appears white as fog. Such fog gradually clears, and so a normal image is observed.
However, while the lens remains foggy as described above, the endoscope cannot be used; therefor, there is a considerable inconvenience due to little progress in testing with the endoscope. Also, in the case where autoclave sterilization is repeatedly carried out or continuously carried out over a long time, such high pressure and high temperature vapor sterilization will cause the joined portions of the objective optical system to deteriorate thereby causing the joined portions of respective constituent parts, which are made of a stainless material to constitute the objective optical system, peel off from one another.
The phenomenon described above is the same with an electronic endoscope, in which CCDs are used as a solid-state image pickup element. Thus, when respective constituent parts of a stainless material on an imaging unit, which includes an objective optical system to be disposed at an end surface of an image incident end of the solid-state image pickup element such as CCDs, are joined together by a conventional adhesive, joined portions of the constituent parts deteriorate to allow entry, of vapor into an interior of the imaging unit, such that an image on a monitor will not appear normal due to fog or the like on the objective lens. Further, in the case where autoclave sterilization is repeatedly carried out or continuously carried out over a long time, joined portions of the respective constituent parts of the imaging unit peel off from one another.
To solve the above-mentioned problem, Japanese Patent Laid-Open No. 212614/1987 has proposed an endoscope of a gas-tight unit construction, in which a cover glass is gas-tightly mounted to an inner cylindrically-shaped armour member provided in an insertion part, and the optical members of an objective optical system or the like are mounted in the armour member to prevent fogging of the lens system of the optical members, deterioration of the lenses and the adhesive. In this prior art, the lens system is subjected to focus adjustment mounted to the armour member in a state.
Also, portions of an endoscope, which should prevent entry of vapor from autoclave sterilization, are gas-tightly joined by soldering, hard brazing, laser welding or the like. Also, in the case where optical members formed of, for example, optical glass are to be joined to a body tube, which is formed of a material such as ceramics to hold such optical members, metallic coating such as gold plating, nickel plating or the like is applied on joining surfaces, and then the joining surfaces are gas-tightly joined together by soldering, hard brazing, laser welding or the like. In addition, gas-tightness indicates one, which can withstand a high pressure and high temperature vapor for autoclave sterilization.
In the above-mentioned prior art, however, it is necessary to use a cover glass having a larger outer diameter than that of a lens in the objective optical system because the cover glass is installed on a tip end side of the objective optical system. Also, while the cover glass is made thin to enable reducing an outer diameter of a tip end of an insertion part of an endoscope to some degree, there are caused problems in the work of the cover glass, gas-tight joining, strength and so on when the cover glass is made thin. Therefore, the gas-tight unit construction is such that the cover glass is larger than the objective lens system. This leads to a great discomfort for a patient because the outer diameter of the tip of the endoscope which has a large angle of visibility and is also the insertion part of the endoscope becomes large.
Further, as described with respect to the prior art, because optical members and a body tube are generally different in coefficient of thermal expansion, the optical members are clamped by the body tube to sometimes break, crack and so on, due to a temperature difference at the time of heating for joining by hard brazing and soldering, and at the time of cooling after the joining when the optical members and the body tube are to be joined to each other by hard brazing, soldering or the like. Also, in some cases, heat produced at the time of the autoclave sterilization exerts forces tending to produce gaps in joined portions between the optical members and the body tube, which are different in coefficient of thermal expansion, such that the joined portions will peel off thereby undermining gas-tightness. Also, where a material such as cover or the like having a coefficient of thermal expansion near that of an optical glass, which is generally used to form optical members, is used to form a body tube, the range of selection for materials for the body tube is made narrow to cause an increase in cost.
The endoscope described in the above-mentioned Japanese Patent Laid-Open No. 212614/1987 needs to use a cover glass, having a larger diameter than that of an objective lens, on the tip end side of the objective lens system mounted to the optical frame provided on the insertion part. Therefore, a problem with such an endoscope is that an outer diameter on the tip of the insertion part becomes large to impose a great discomfort on a patient.
It is an object of the invention to provide an endoscope device capable of adjusting the focus of the optical members when assembled, making the outer diameter of a tip of the insertion part small, and preventing entry of vapor into the optical frame of the insertion part even when autoclave sterilization is performed.
Also, it is another object of the invention to provide an endoscope device capable of preventing optical members from being broken by a difference in coefficient of thermal expansion upon temperature change generated on the optical members and a body tube at the time of the optical members and the body tube are being joined together even when the optical members and the body tube have different in coefficients of thermal expansion, while and maintaining gas-tightness in the joined portions.
Further, it is another object of the invention to provide an endoscope device capable of preventing the joined portions from being broken due to a difference in their coefficients of thermal expansion by temperature changes generated on the optical members and the body tube at the time the autoclave sterilization is applied to the endoscope even when the optical members and the body tube have different coefficients of thermal expansion, while maintaining gas-tightness in the joined portions.
Also, it is another object of the invention to provide an endoscope device, which can perform focus adjustment on optical members as assembled, and make small a tip end portion of an insertion part in outer diameter to prevent entry of vapor into the tip end portion even when autoclave sterilization is carried out.
Also, it is another object of the invention to provide an endoscope device capable of preventing a cover glass and an objective lens frame (a first frame body) from being broken by temperature change generated on the cover glass and the objective lens frame when the cover glass and the objective lens frame are being joined together and when the autoclave sterilization is applied on an endoscope even when the cover glass and the objective lens frame have different coefficients of thermal expansion, while maintaining gas-tightness in the joined portions.
An endoscope device for autoclave sterilization, according to the instant invention, comprises a first unit composed of an optical member and having a first frame body for gas-tightly holding the optical member, the first unit being arranged at a tip end of the endoscope device; a second unit having a second frame body and a portion being adapted to fit on a fitting portion of the first unit and to be adhered and fixed thereto, the second unit arranged at a tip portion of the endoscope provided rearwardly of the first unit and cooperating with the first unit to constitute an optical unit; and a covering member having a first joined portion for gas-tight joining of the first frame body of the first unit, and a second joined portion for gas-tight joining of the second frame body of the second unit, the covering member covering the first frame body of the first unit and the second frame body of the second unit.
Also, an endoscope device for autoclave sterilization, according to the present invention, comprises a first frame body having gas-tightly mounted thereon an optical member, and arranged at a tip end of the endoscope device; a second frame body mounted to be movable in position relative to the first frame body in a direction of the optical axis, the second frame body being positionally adjustable in the direction of the optical axis to be made stationary; and a cylindrical member adapted, to cover the first frame body and the second frame body, and gas-tightly joined to the first frame body and the second frame body, respectively.
Further, an endoscope device for autoclave sterilization, according to the present invention, comprises a first metallic frame body having gas-tightly mounted thereon an optical member by brazing or soldering, and arranged at a tip end of the endoscope device; a second metallic frame body mounted to be movable relative to the first metallic frame body in a direction of the optical axis, the second metallic frame body being positionally adjustable in the direction of the optical axis to be made stationary; and a cylindrical member adapted to cover the first metallic frame body and the second metallic frame body, and gas-tightly joined to the first metallic frame body and the second metallic frame body, respectively.